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Spiny cocklebur
Row Crop
(Xanthium spinosum L.)
Gary N. Ervin, Ph.D., Department of Biological Sciences, Mississippi State University
John D. Madsen, Ph.D., Geosystems Research Institute, Mississippi State University
Ryan M. Wersal, Geosystems Research Institute, Mississippi State University
Fig. 1. Spiny cocklebur spreads by seeds
clinging to animal fur or human clothing.
Fig. 2. Spiny cocklebur has male and female flowers
on the same plant.
Fig. 3. Spiny cocklebur plants grow to
five feet tall.
Introduction
Problems Created
Spiny cocklebur is an annual plant found in highly disturbed habitats and farm areas. The burs (fruits) of this species become
tangled in the fur of livestock, increasing costs to the consumers of wool products. It competes with crops and is a nuisance
when growing with hand-harvested crops. The seeds and seedlings of spiny cocklebur are poisonous if consumed, and they are
particularly toxic to swine and horses.
Regulations
Spiny cocklebur is listed as a “B” designated quarantine weed in Oregon and a class “C” noxious weed in Washington. In Arkansas, the genus Xanthium is listed as noxious weeds, likely more for spiny cocklebur’s congener Xanthium strumarium (rough
cocklebur), which has a much wider distribution in the state.
Description
Vegetative Growth
Spiny cocklebur is an annual plant that blooms in summer. It grows to 5’ tall with striate stems that are yellowish or brownish
gray. The leaves may be entire or toothed or lobed. The lower surface of the leaves is covered with white hairs, and the upper
leaf surface is white-veined. Leaves are 1’’to 3’’ long and have a 3-forked spine at the leaf base, giving this species the common
name “spiny” cocklebur.
Flowering
Male and female flowers are separated, but they occur on the same plant. Male flowers form above the female flowers in the
axils of the uppermost leaves. Female flowers occur in the leaf axils lower on the plants. As the fruit develops from the female
flowers, the bur that bears a beak and hooked bristles begins to develop. On average, plants produce 150 burs, each containing
two seeds.
Dispersal
A primary dispersal mechanism for spiny cocklebur is “hitchhiking” on animal fur or human clothing. The fruits float in water, and
can also be effectively dispersed by water. Seeds can be spread by clinging to feedsacks or in contaminated hay. Ungerminated
seeds remain viable for several years in the soil.
Spread by
Spiny cocklebur is spread by livestock and the transport of livestock from infested fields to uninfested fields.
Habitat
Spiny cocklebur is found in open and disturbed waste places. It can be found growing along roads, barnyards, pastures, vacant
lots, and other disturbed sites. It also can be common around moist disturbed sites such as along ditches, canals, river terraces,
and floodplains.
Distribution
United States
Spiny cocklebur is native to South America, but now is found throughout the contiguous U.S., though it is not recorded from Arkansas, Louisiana, Minnesota, North Dakota, Oklahoma, South Dakota, Vermont, Wisconsin, or Wyoming.
MidSouth
Spiny cocklebur is not a widespread pest in the MidSouth. It has not been recorded from Arkansas or Louisiana, and it is only
known from one county each in Mississippi, Tennessee, and Alabama.
Control Methods
Biological Control
Table 1. Suggested chemical control
There are no approved biological control agents for this species.
methods for spiny cocklebur.
Chemical Control
Spiny cocklebur is susceptible to a variety of herbicides that are commonly used for broad- Herbicide
Foliar spray rate
leaved weed control. Several auxin mimicking herbicides can be used such as 2,4-D at a
per acre
rate of 1 to 2 quarts per acre, triclopyr at a rate of 3 to 4 pints per acre, and 2,4-DB at 0.8 to
1-2 quarts
1 pint per acre. The use of an auxin mimicking herbicide may be more selective for grass
2.4-D
species than other herbicide options. Glyphosate is effective at rates of 2 to 4 quarts per
0.8-1 pint
acre. Imazapyr can be applied at a rate of 3 to 4 pints per acre, and imazaquin can be ap- 2,4-DB
plied at 1.8 to 2.4 ounces per acre for spiny cocklebur control. The use of glyphosate, ima- Glyphosate
2-4 quarts
zapyr, and imazaquin will typically result in non-target plant injury. Herbicide spray solu3-4 pints
Triclopyr
tions should contain an appropriate surfactant to ensure complete leaf wetting. Herbicide
applications should be made to young 3 to 5 leaf plants during active growth to maximize
1.8-2.4 oz.
Imazaquin
treatment efficacy.
3-4 pints
Imazapyr
Mechanical Control
Plants can be hand pulled before burs form; however, after the formation of burs plants
should be burned to destroy the seeds. Even unripe seeds can mature on cut or pulled plants. Mowing can be effective, but as
with hand pulling, mowing should be carried out before burs are formed. Burning would be effective at removing standing plants
and killing seeds; however, this method is rarely used in controlling spiny cocklebur.
Physical Control
No physical controls are currently recommended for Spiny cocklebur.
References
Arkansas State Plant Board. 1997, revised 2006. Regulations on Plant Diseases and Pests. Circular 11, Final Rule. Online
resource at http://www.plantboard.org/plant_pdfs/plantdiseasereg.pdf accessed [26 February 2009].
Oregon Department of Agriculture. 2007. State noxious weed list and quarantine. Online resource at http://www.oregon.gov/
ODA/PLANT/WEEDS/lists.shtml#Noxious_weed_policy___list accessed [26 February 2009].
Pitcher, D. 1989. The Nature Conservancy element stewardship abstract for Xanthium spinosum. The Nature Conservancy, Arlington, VA. Online resource at http://tncinvasives.ucdavis.edu/esadocs/documnts/xantspi.pdf accessed [26 February 2009].
USDA, NRCS. 2009. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA. Online resource
at http://plants.usda.gov accessed [26 February 2009].
Washington State Legislature. 2008. State noxious weed list and schedule of monetary penalties. Online resource at http://
apps.leg.wa.gov/WAC/default.aspx?cite=16-750 accessed [26 February 2009].
John D. Madsen, Ph.D.
Geosystems Research Institute
Mississippi State University, MS 39762-9555
(662) 325-2428
[email protected]